As a virtual technique for a storage device, there is a storage device which creates a pool (a hierarchical pool) using plural kinds of storage devices having different performances (see, for example, Patent Literature 1). In the hierarchical pool, a storage region of a virtual logical volume is allocated in a data unit called a page and a storage device in which the page is arranged is periodically switched according to an access characteristic (I/O number (IOPS), etc.) per unit time in the page unit (see, for example, Patent Literature 2). Specifically, a storage region of a high-performance storage device (disk device) is preferentially allocated to a page having a high access characteristic. Consequently, compared with a case in which data is allocated from a single type of a storage device in a virtual logical volume unit, in a case in which a virtual logical volume in a hierarchical pool is configured, when a configuration satisfying a performance requirement and a capacity requirement of a system is designed, a necessary capacity of a high-performance storage device decreases and it is possible to reduce storage management cost.